Lathe update/questions



    Oops!
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    You mean the longitudinal motion? I'm not used to having *any* graduations on that -- except on the Unimat SL-1000 which had only a hand-cranked full-length leadscrew.

    Hmm ... does the set of possible threads include 10 TPI? Perhaps you could *make* replacement leadscrews and nuts to fit it.

    Well ... IIRC, the Jet from back around 1990 or so had the same threads, so I suspect that they *all* come with either these threads ore metric threads on the leadscrews.

    Good Luck,         DoN.
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Don,

Yes, and the markings are not of much value.
> except on the Unimat SL-1000 which had only a

I assume that most lathes use a rack and worm gear to reserve the leadscrew for threading, right???

I thought of that, and it is indeed a possibility for the future. However, given the responses in this thread, it appears that I will not have much trouble over it. I simply did not want to tell myself that and regret it later.

I was afraid someone would use the J-word :) Having had trouble with them in the past, I doubt I would even consider a Jet machine. I _hope_ I would not even consider a Jet machine. I think I would sooner buy another Buick. The hostility is of course *not* directed at you, and your point is well-taken.
The Grizzly version of the lathe in question appears to be exactly the same base with some nice looking dials and handles and some paint. I am waiting for a response from them about the dials, but would probably have to wonder whether they are indeed a metric "equivalent." Also, we have Richard's "friend of mine" comment, and so far no such favorable review of a Grizzly.
However, the question stands: if anyone knows of a true 10 tpi lathe in the same class, I will take a look as I am doing with the Grizzly. So far, I am leaning toward keeping the machine.
Bill
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    Indeed. If you want precision in longitudinal motion, you clamp either a turret bed stop or a dial indicator to the bed parallel to the ways. You could do with a micrometer bed stop and a set of spacers if you don't need it very often.

    Yes -- except that the inexpensive ones are likely to use the leadscrew's threads for feeds too -- requiring more changing of speeds to get to a fine enough feed. As examples:
1)    The Atlas/Craftsman 6x18 lathe (long out of production) -- had only     the leadscrew and a basket of change gears. You used the     half-nuts for both feed and threading, and if the change gears     were set up for threading they would be too fast for practical     feed if you are after a nice finish. So -- you could not even     get away with a "good enough" and leave the gears set as they     were.
2)    My 12x24" Clausing (also long out of production) has both a     quick-change gearbox making it easier to change feeds and speeds     (and less messy -- you wind up with rather black hands changing     gears frequently if you keep them properly lubed), and separate     feed controls on the apron. This machine used the same     leadscrew to power the feeds, but not the threads on the     leadscrew. Instead, it had a keyway milled in the side of the     leadscrew the full length. The apron had a sleeve in bearings     which surrounded the leadscrew with a key engaging the keyway,     and a worm gear on the OD of the sleeve. Gears in the apron     picked up the rotation of the leadscrew through the worm and     were carried to either the handwheel to move the carriage via     the rack and pinion (and much slower than the half-nuts would at     the same speed so you don't need to change feed gears as much),     or to the cross-feed (even slower for fine finish when facing     off.
    Fancier systems would have a separate rod with the keyway for the feed, and sometimes a second leadscrew and half-nut set for metric threading instead of Imperial threading. I would like to have this capability. Metric threading really should have a metric thread leadscrew to allow the threading dial to be useful.

    O.K. I have made mistakes using the 0.125"/rotation handwheels on the machine at work before I retired. I prefer the 0.100"/rotation on my Clausing. But I do have an inexpensive DRO (The Shooting Star) which I plan to eventually mount on the Clausing. Among the advantages are accurate position even when leadscrews are badly worn, and the ability to switch the readout between reading diameter removed and reading radius removed depending on what you need to do. As it is, I keep a digital caliper and an HP-15C calculator handy for keeping track of what dimension I am sneaking up on. I tend to zero the calipers at the target diameter so my readings tell me how much needs to be removed, and the divide the reading by two to get the necessary dial reading change.

    Just which model of Jet did you have problems with? The lathe which I used was essentially the brother of yours -- same castings and features, and those had a pretty good reputation compared to the 9" and 7" ones, which were very limited.

    Note that an 8 TPI thread works out to precisely 3.1750 mm thread pitch -- not exactly the most convenient value, but precise. :-)

    At this point -- why not keep it? I don't think that you will find anything with a 10 TPI cross-slide leadscrew which is not made in the USA -- which mostly means older machines like my 12x24" Clausing, which was made in 1957.
    Enjoy,         DoN.
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DoN. Nichols wrote:

That seems like an obvious solution to the problem. The lathe of the hour has a separate shaft with keyway to drive the feeds.

No question about that.

The big example is an H/V bandsaw. My real gripe is their reaction to my pointing out a serious design flaw in the emergency cutoff. They really showed their colors on it, and it did fail as I predicted. Prior to that, I bought one of their woodworking jigs. Never again.

I am leaning toward keeping it. I would have preferred to hash this out pre-purchase, but this has been a helpful discussion, and if I do keep it, it won't be because I made foolish assumptions about how I will use the dials. It sounds like the primary deficiency will be in setting dials to agree after a witness cut, but I can create a chart for converting diameter to dial readings to simplify it.
Thanks!
Bill
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<snip>

Just get .1 dials and put them on your existing screws!
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Tom,

Let's keep the satire to a minimum: we're talking about important things like machine tools here, not something frivolous like choosing a leader for the free world.
Bill
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I couldn't resist pulling your leg! However, the remark had some validity. My dials mean nothing to me until I start getting close to where I need to be, and then nothing when I get really, really close. I guess it depends on what the job is but I rely on my measuring device and an intuitive twist of the screw.
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My pocket scale is the ticket until we get close enough to care.
Wes
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Wes wrote:

Exactly what I do on a mill, but the difference is that "caring" usually means matching the dial to the last two digits on the drawing. If those walked every revolution, I'd go nuts. If most work "take another 0.011," then the dial range is not a big deal.
Bill
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Tom,

That seems to be the evolving story, most work is measure/remove. I will look around one more time, but I will probably end up keeping the machine sitting in my garage.
Bill
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I'd just accept it and move on. I have used a lot of lathes. Each one is a bit different and you quickly adapt to it. The diameter of your dials have an effect too on how fine you can position the cross slide. Big ones are nicer than small diameter ones. We are only talking 25% coarser in pitch anyway.
Now what really irritates me is that every lathe I've used except for mine, pulling up on the half nut lever disengages the split nuts :(
Wes -- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
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Bill, I personally think the lathe is junk. How many spindle speeds do you have ?(probably 9), you need 12. How fast is the slowest speed in back gear? You really need around 30 rpm. You probably have around 90 rpm and that is too fast for a 12" machine. How many threads will it cut? (38). A good machine will cut 80 in inch alone. An inch machine will have a 4 or 8 TPI lead screw for the carraige and a 10 TPI for crossfeed and compound. The good chinese machines have dual graduations on the carraige and compound both inch and metric. Most metric machines have .02 graduations. Check the thread dial. You probably have a metric machine. If you elect to keep it, you MUST completely dissassemble it and clean it. It will be full of chips, swarf and grit. Assume nothing, check everything including spindle parrallelism to the bed ways. You get what you pay for. If you ever get a chance to use a class machine, you will never own the one you just bought. Steve

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Bill, Please do not get me wrong. I am not prejudiced against Chinese machines. They are great value for money, but you need to understand what you are buying. I have had very good luck with some, but I have really seen some junk. Buyer beware! The good machines are usually made in Taiwan and the junk made on the mainland, but that rule is very gray now with the much larger trade between Taiwan and the mainland. I have witnessed extensive trade volume with China through a close associate. On some lots of machinery, we have seen 1 in 4 received as failures in some shape or form! Worst of all, most resellers never carry parts. Do not expect after sales support! Steve

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Steve Lusardi wrote:

I take it you've never seen any of the junk made here in the USA?
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I personally have not seen any junk tools made in the USA.
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On Sun, 27 Apr 2008 12:34:18 -0500, with neither quill nor qualm,

Then you haven't been buying them here for long enough, Ig.
-- Happiness in marriage is entirely a matter of chance. If the dispositions of the parties are ever so well known to each other or ever so similar beforehand, it does not advance their felicity in the least. They always continue to grow sufficiently unlike afterwards to have their share of vexation; and it is better to know as little as possible of the defects of the person with whom you are to pass your life. -- Jane Austen, Pride and Prejudice, 1811
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Well I have not seen a junk tools made either here or in Europe. Of course, some are better than others, but never junk. However, it stands to reason that there must be some junk made in the first world even if I haven't seen it, but it sure in hell isn't 1 to 4, which I see regularly from mainland China. Steve
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On Sun, 27 Apr 2008 12:34:18 -0500, Ignoramus30765

Neither have I, actually...and Im pretty tool savvy.
Gunner
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By junk, I mean the tool either did not function as intended, or broke much before its expected lifetime, under normal use. I cannot recall a single instance of a US made tool failing in this manner.
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On Sun, 27 Apr 2008 17:31:29 -0500, with neither quill nor qualm,

If nothing else, you never bought anything from Searz branded Crapsman in the late 70s or early 80s, or anything not branded Crapsman at any other time. Then again, lots of that crap is Chiwanese or Indian, and both those sources have been producing a MUCH better product in the last decade or so.
-- As a curmudgeon, I grok that in its entirety. --LJ
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